Poster: Water Relations

Abs # 213: AtTPS1, the Arabidopsis trehalose-6-P-synthase gene, regulates glucose sensing and ABA signaling genes

Presenter:	Iturriaga, Gabriel , iturri@cib.uaem.mx
Authors	Iturriaga, Gabriel  (A)   Avonce, Nelson  (A)   Mascorro-Gallardo, Oscar  (C)   Van Dijck, Patrick  (B)   Thevelein, Johan M (B)
Affiliations:	(A): Centro de Investigacion en Biotecnologia-UAEM (B): Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit Leuven (C): Departamento de Fitotecnia, Universidad Autonoma Chapingo

In Arabidopsis, trehalose is present at almost undetectable levels excluding its role as an osmoprotectant. Here we report that overexpression of AtTPS1 in Arabidopsis using the 35S promoter leads to a low trehalose accumulation. Nevertheless, transgenic plants displayed dehydration tolerance, glucose- and ABA-insensitive phenotypes in seedlings and delayed flowering in adult plants. Transgenic seedlings germinated on glucose are visibly larger with green well-expanded cotyledonary leaves and fully developed roots, in contrast to wild type seedlings which show growth retardation, short unexpanded leaves without chlorophyll and absence of root elongation. When transgenic seeds were germinated without prior cold treatment, their germination rate was higher compared to wild type seedlings, suggesting an arrested dormancy. Germination in the presence of different concentrations of ABA revealed higher germination rate for transgenic plants overexpressing AtTPS1, although ABA concentration remain unchanged compared to wild type plants. Expression analysis of several genes in transgenic plants showed up-regulation of ABI5, HXKI, HXKII, RBSC and APL3 genes, whereas in the presence of glucose ABI4 was down-regulated. Analysis of AtTPS1 in HXK-antisense or HXK-sense transgenic lines, revealed its involvement in HXK-dependent glucose signaling pathway. These data strongly suggest that AtTPS1 has a pivotal role in the regulation of glucose sensing and ABA signaling genes during vegetative development.